The present invention relates to a resealable plastic packaging container consisting of a packaging tray and a lid film which is sealed to the packaging tray such that it can be at least partly peeled back.
Packaged products, especially foods, are sold increasingly today in plastic packaging containers. These plastic packaging containers have a packaging tray in which the packaged product is situated and a lid film. The lid film is sealed to the packaging tray. As the packaged product often is not immediately consumed after opening, it is advantageous if the packaging container can be resealed after opening.
There has therefore been no lack of attempts in the past to create resealable packaging containers. As examples we need merely mention EP 0,564,695, DE 39 25 746, EP 0,386,490, DE 39 41 183, EP 0,408,516, WO 97/05023, EP 0,716,986, EP 0,595,368, EP 0,579,262, EP 0,506,295, EP 0,427,513, EP 0,427,512, EP 0,385,565, EP 0,381,329 or EP 0,379,927 in which either processes or devices are taught for the production of a resealable packaging container and/or the resealable packaging container itself. All the resealable packaging containers disclosed in the above-mentioned publications have the disadvantage that they are either complicated to produce and/or difficult to reseal.
The object is therefore to provide a resealable plastic packaging container which does not have the disadvantages of the prior art.
According to the invention, said object is achieved by providing a resealable plastic packaging container consisting of a packaging tray and a lid film which in the sealing area is sealed to the packaging tray such that it can be at least partly peeled back and the plastic packaging container has at least one hook and loop closure whose two complementary parts are arranged opposite each another on the packaging tray and on the lid film and by means of which the plastic packaging container can be resealed after the peel-back seal has been opened.
In the meaning of the invention, a packaging tray is any packaging tray familiar to the person skilled in the art which is produced from a thermoplastic and dimensionally stable single- or multi-layer film, preferably as conventionally used for the packaging of foods.
On at least one of its two surfaces the film must have a sealing layer which can be peeled back. Preferably used as the sealing layer is a mixture of LDPE (low-density polyethylene) and a polybutylene. The mixture preferably contains 15 to 30% by weight and especially preferably 20 to 28% by weight polybutylene. The polybutylene preferably has a melt flow index (MFI) ranging from 0.3 to 2.0 g/10 min (190xc2x0 C. and 216 kg according to ASTM 1238).
It is particularly preferred to produce the packaging tray from a multi-layer film with an expanded carrier film, preferably from an expanded polyolefin film, especially preferably polypropylene film, optionally with a gas barrier layer.
In a particularly preferred fashion, the packaging tray is produced from a film as disclosed in the patent application with the German Patent Office File No. 198 40 046.2. This patent application is hereby incorporated by reference and is thus considered part of the disclosure.
After filling with the product, the thermoformed, preferably deep-drawn packaging trays are sealed with a lid film familiar to the person skilled in the art. Especially suitable as lid films are multi-layer films with a gas barrier layer of ethylene-vinyl alcohol copolymer, preferably consisting of polyethylene terephthalate/-adhesion-promoting layer/polyethylene/adhesion-promoting layer/ethylene-vinyl alcohol copolymer/adhesion-promoting layer/polyethylene, whereby the polyethylene terephthalate layer can be replaced by polypropylene.
If the lid film of the packaging container according to the invention does not have a recess or elevation, it can also have SiOx as the gas barrier layer. The lid film is then preferably composed of PET/SiOx/adhesion-promoting layer/polyethylene.
Such lid films are distinguished by their especially good transparency and a high resistance to breakage when folded. The package packaging tray sealed in this way has an especially good gas barrier effect.
According to the invention, the lid film is sealed in the sealing area to the packaging tray such that the lid film can at least be partly peeled back. For the peel-back seal, the lid film is sealed to the packaging tray at a temperature of 130xc2x0 C. to 150xc2x0 C., and at a pressure of 3xc3x97105 to 8xc3x97105 N/m2, preferably 4.0xc3x97105 to 5.0xc3x97105 N/m2. If the packaging containers according to the invention are to have a non-peel-back, i.e. permanently sealed, part of the sealing area, the permanent seal is preferably executed at an least 10xc2x0 C. higher temperature than the peel-back seal and at preferably double the pressure. A permanent seal in the meaning of the invention is a seal whereby the force required to detach the lid film must be at least five times higher than in the area of the peel-back seal.
The sealing area on the packaging tray is preferably situated on a horizontal plane above the packaged product and preferably extends on this plane around the entire packaged product. On a polygonal plastic packaging container, the lid film can be permanently sealed to the packaging tray on preferably at least one side of this polygon whereas the lid film in the remaining sealing area is peelably sealed to the packaging tray. On a round packaging container, preferably 5 to 25% of the sealing area can be provided with a permanent seal.
According to the invention, the resealable plastic package has at least one hook and loop closure by means of which the plastic packaging container can be resealed after the peel-back seal has been opened. The hook and loop closure can be any hook and loop closure familiar to the person skilled in the art in any desired form. Such a hook and loop closure consists of two complementary parts which engage and thus form a firm but releasable joint. The two complementary parts of the hook and loop closure are arranged opposite each another on the packaging tray and on the lid film respectively. After the packaging container has been opened, it can be sealed again by pressing the part of the hook and loop closure arranged on the lid against the part of the hook and loop closure arranged on the packaging tray.
The hook and loop closure can be joined to the lid film or packaging tray in any desired manner familiar to the person skilled in the art. However, it is preferably sealed on, or attached by hotmelt adhesive, and very especially preferably bonded.
The hook and loop closure is preferably made of polypropylene.
In a preferred embodiment, the hook and loop closure is arranged outside the sealing area or is at least arranged at a position where the seal can be peeled back.
In an especially preferred embodiment of the plastic packaging container according to the invention, the lid film has at least one elevation and the packaging tray at least one complementary recess which are arranged opposite each other and on each of which one part of the hook and loop closure is arranged.
In an equally especially preferred embodiment of the plastic packaging container according to the invention, the lid film has at least one recess and the packaging tray at least one complementary elevation which are arranged opposite each other and on each of which one part of the hook and loop closure is arranged.
In another preferred embodiment, either the lid film or the packaging tray has a recess in each of which one complementary part of the hook and loop closure is arranged.
However, it is also possible to arrange the complementary parts of the hook and loop closure without recess or elevation on the lid film and packaging tray.
If a permanent sealing area is provided, the hook and loop closure(s) is/are arranged on the plastic packaging container such that they are arranged outside the area of the permanent seal and preferably diametrically opposite. The advantage of this arrangement is that the lid film can then be tensioned and then firmly yet re-releasably connected with the hook and loop closure(s).
The plastic packaging container according to the invention can preferably have additional means, e.g. opening aids and/or means for resealing the packaging container. Such means are preferably a zip-fastener as disclosed in EP 0 621 197 A1, a lip seal, a clip seal as disclosed in EP 0 427 512, or a knob as disclosed in the parallel application with the internal File No. CH 8007. These publications and the parallel application are hereby incoporated by reference and are thus part of the disclosure.
Foods, preferably solid, e.g. fresh or cooked meat products, are preferably packaged in the packaging container according to the invention.
With the plastic packaging container according to the invention it is possible to reseal an opened packaging container firmly yet re-releasably. The packaging container is easy for the user to seal and open. The plastic packaging container is simple and inexpensive to produce.